Definition from Wiktionary, the free dictionary
- (chemistry) tritium-deuterium, a type of hydrogen (H2) molecule
- The ISO 3166-1 two-letter (alpha-2) code for Chad.
- Touch Down
- Tardive Dyskinesia
- Teachta Dála, a member of Dáil Éireann, the lower chamber of the Parliament of the Republic of Ireland. (See usage notes below in Irish section).
- Territorial Decoration (previously awarded to officers who had more than 12 years commissioned service in the Territorial Army (UK))
- (travel) ticket designator
- IPA: /tede/
TD m pl
- Teachta Dála, a member of Dáil Éireann, the lower chamber of the Parliament of the Republic of Ireland.
Usage notes 
- In English the abbreviation TD is normally used, with TDs as the plural (the full form of which in Irish is Teachtaí Dála).
- The letters follow the name of the member when used as a title, eg, Mr Bertie Ahern TD.